1. Field of the Invention
This invention relates, in general, to snowmobile and other ski vehicle braking and steering systems. More specifically, the invention relates to braking and steering systems that improve control of the vehicle's forward or backward motion even when the conventional braking method, that is, slowing or stopping the drive track for snowmobiles, for example, fails to adequately control the vehicle.
2. Related Art
Snowmobiles, for example, are conventionally slowed or stopped by slowing or stopping the drive track, that is, the endless belt that moves against the snow or ground to power the snowmobile. Because the drive track causes the snowmobile's movement relative to the snow/ground, the drive track is conventionally used to achieve slower movement or to stop movement of the snowmobile. Using this as the sole breaking method, however, can be ineffective and even dangerous in conditions in which the drive track's frictional contact with the snow or ground is not optimum. For example, when the drive track is "clogged" with snow, engagement of the track with the snow on the snowmobile's course is not always sufficient to quickly slow or stop the snowmobile. Or, when the snowmobile is traveling downhill or on icy terrain, the track tends not to grip the terrain adequately. Under these conditions, therefore, the track tends to slip rather than grip the terrain, and the conventional braking system is inadequate. Also, the conventional braking system provides no steering capability, and, in fact, tends to interfere with steering because it tends to lock up the drive tracks and cause skidding.
One attempt at a solution to the braking problem has been posed in the patent literature, as shown in U.S. Pat. No. 5,673,772 (Martin, Oct. 7, 1997). Martin discloses a ski-type runner system which includes a downwardly extendable flap at the rear end of each runner that may be actuated to drag into the snow. Martin teaches that the two flaps are actuated in unison so that balanced braking force is applied to each trailing ski end on both sides of the snowmobile. It is understood, however, that the rearward flap of Martin adversely effects the handling characteristics of the snowmobile during operation.
Another attempt at a solution to this braking problem in shown in U.S. Pat. No. 5,931,481 (Hoffman, Aug. 3, 1999). Hoffman discloses a snowmobile braking system with two (2) blades which are downwardly extendible from each side of the central portion of a ski. Only one of the snowmobile's two skis is equipped with the braking system. It is expected that the single-ski brake of Hoffman will also adversely affect the handling characteristics of the snowmobile during operation.
Still, an effective and safe ski vehicle braking and steering system is needed to improve handling in icy or downhill conditions, for example. Such a braking and steering system is needed that does not depreciate or interfere with handling of the ski vehicle.